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SEPTEMBER 2009 daily and monthly summary

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SEPTEMBER 2009
October
1st - 4th
Windy and showery. 1st, LP 990 hPa Hebrides, cold front crosses midday bringing two moderate rain showers. 2nd LP ex Tropical Storm 'Danny' 994 hPa by Southern Ireland, 3 heavy rain showers morning an afternoon with steady moderate rain from the early evening to early morning 3rd, sunny periods and light rain showers afternoon. 4th, light rain shower pre dawn.
5th - 12th
5th, HP 1027 hPa W of Biscay, LP 996 hPa S of Iceland and 995 hPa Southern Scandinavia. Mainly cloudy 5th and 6th. 7th: HP 1026 hPa Poland, LP 985 hPa far to W of southern Ireland. 9th: HP 1036 hPa at 50N 20W pushing ENE, weakening cold front crosses SE England with just a trace of rain from a shower. 10th to 12th: HP 1036 hPa near N Ireland and Scotland, mixture of sunny periods and cloud.
13th - 17th

13th, mainly cloudy and sometimes dull. 14th: HP 1034 hPa S Norway and Shetland, LPs 1004/1009 hPa W Mediterranean, one light shower am giving a trace of rain. 15th, occluded front brings moderate and heavy rain from mid morning lasting two hours followed by some drizzle. 16th, light rain showers with one heavier after midnight to 04.30h.

18th - 23rd

18th, sunny after a cloudy start. 19th: light fog am clearing to give sunny spells. 20th: HP 1029 hPa NNE of Azores, HP over C and E Europe, LP 975 hPa SW of Iceland, some mist first thing then mainly cloudy. 22nd: HP stretches from Biscay to C Europe, LPs track far to the N.

24th - 30th

24th, a little drizzle just past midnight followed by a sunny day. Fri 25 - Sun 27th, little synoptic change, HP stretches from Azores 1032 hPa to E Europe 1029 hPa, virtually unbroken sunshine during these days. Mainly cloudy 28th. 29th, HP 1028 hPa to W of Ireland. 30th cloudy and sometimes dull until near the very end of daylight.

SEPTEMBER 2009 MONTHLY SUMMARY
ACTUAL TEMPERATURE
 AVERAGE
 Daily Maximum
20.2
  ºC ( + 1.2C )*
 Daily Minimum
11.6
  ºC ( + 1.1C )*
 Daily Mean
15.26
  ºC ( c. +0.9C )
 EXTREMES
 High Maximum
27.2
  ºC (   8th )
 Low Minimum
6.1
  ºC ( 27th )
 Low Maximum
16.2
  ºC ( 15th )
 High Minimum
15.9
  ºC (   8th )
 
   
 Days with max => 25 °C
1
   ( ±0 )
 Days with max in range 20 - 25 °C
15
   ( +5 )
 Days with max < 20 °C
14
   ( -5 )
 
PRECIPITATION
 Monthly Total
24.3
  mm ( 44% )
 Days with measurable precip
7
  Days ( -4 )*
   ...of which, days with >= 1.0 mm
4
  Days ( -5 )*
   ...and days with hail observed
0
  Days  
 
   
 Days with Thunder
0
  Days  
 RAIN RATE & EXTREMES
 High Rain Rate
30.0
  mm/hr (  2nd )
 High Rain Total in 1 day
10.8
  mm (  2nd )
 High Rain Total in 1 hour
5.1
  mm ( 15th, 11h40)
 EVAPO-TRANSPIRATION
 Total for month
66.8
  mm  
 High Total for 1 day
3.9
  mm ( 8th )
APPARENT TEMPERATURE
 Low Wind Chill
6.1
  ºC ( 27th )
 DAVIS HEAT INDICES THW & THSW
 Low Temp/Hum/Wind Index
6.0
  ºC ( 27th )
 High Temp/Hum/Wind Index
26.1
  ºC (   8th )
 High Temp/Hum/Sun/Wind Index
32.0
  ºC (   8th )
 
DEWPOINT & HUMIDITY
 High Dewpoint
15.1
  ºC ( 19th )
 Low Dewpoint
4.0
  ºC (   4th )
 Average Dewpoint at 14h
9.9
  ºC  
 Low Relative Humidity
29
  % (   8th)
 Average RH at 14h
55
  %  
WIND SPEED & DIRECTION
 Monthly Average
1.7
  mph  
 Windiest day (Average)
6.0
  mph ( 3rd )
 Highest Gust
26
  mph ( 3rd )
 Dominant Direction
N
  ( 31% )
 
BAROMETER
 Monthly Mean
1020.7
  hPa  
 High Barometer
1035.9
  hPa ( 11th )
 Low Barometer
993.3
  hPa (   3rd )
SUNSHINE
 Max Sensor Exposure to direct sun
8.5
  hours/day (12-13 possible)
 Calculated Monthly Sunshine Hours
135.1
  hours  
 Estimated Actual Hours (approx)
152.0
  hours  
 Sunniest Day Measured
8.3
  hours ( 8th )
 Days with no sunshine
1
  Days  
 
FOG
 Number of Days with Fog
2
  Days  
NEW RECORDS SET THIS MONTH
 
‡ SUN: Sunshine hours are calculated approximately and solely from solar radiation readings, but note that the solar sensor's exposure to sunshine is limited. The sensor receives only up to 60% of total possible sunshine exposure this month due to obstruction. There is no allowance for sunshine by visual observation only, so the sunniest day figures above can be very significantly less than the actual daily sunshine duration.
THW = Shaded Heat Index calculated with cooling/warming effect of wind and humidity to give an apparent temperature.
THSW = Unshaded Heat Index calculated with cooling/warming effect of wind, humidity and full direct sunshine to give an apparent temperature.
EVAPO-TRANSPIRATION is drying effect due to sun and wind, and is equivalent to "negative rainfall"
   DAILY STATS SEPTEMBER 2009
 
TEMPERATURE ºc
HUMIDITY
SUN ‡
PRESSURE
RAINFALL
WIND SPEED
DIRECTION
  WEATHER
 NOTES ‡
DATE
Low
(21-09h)
High
(09-21h)
Temp at 14.00z
RH %
at 14.00z
Dewpoint ºc
at 14.00z
Bright
sun hrs
hPa   †
at 14.00z
Day Total
(mm)
Average
(mph)
Max Gust
(mph)
Dominant
(Compass)
  Precipitation
 type etc ‡
                       
1st
 14.8 20.2 19.1 55 9.9 5.8 1007.3 ST 1.0 4.7 24 SW  SHRA
2nd
 13.6 18.4 17.6 69 11.8 1.7 1007.0 F 10.7 2.9 18 SW  SHRA+ & Rain
3rd
 12.7 18.3 15.6 70 10.1 6.0 1001.0 RS 0.8 6.0 26 SW  SHRA pm
4th
 10.1 18.0 17.2 47 5.8 5.3 1008.3 R 0.5 3.0 18 SSW  SHRA am
5th
 9.7 19.4 19.0 45 6.8 4.3 1021.2 ST 0.0 2.0 16 SSW  Sunny am
6th
 12.6 19.6 18.7 54 9.2 3.8 1021.4 F 0.0 1.8 18 SSW  Cloudy
7th
 12.0 24.2 23.8 52 13.4 7.3 1017.8 ST 0.0 1.6 13 SW  Sunny periods
8th
 15.9 27.2 26.4 34 9.3 8.3 1017.1 FS 0.0 2.4 17 SW  Sunny
9th
 14.4 21.4 20.3 47 8.6 3.7 1027.9 RS 0.0 1.7 13 N  Cloudy
10th
 10.4 21.1 20.5 46 8.5 5.3 1033.7 ST 0.0 1.9 14 N  Sunny periods
11th
 10.7 21.1 19.9 48 8.6 4.7 1033.5 F 0.0 1.2 14 N  Cloudy
12th
 12.8 21.7 18.2 43 8.6 5.3 1028.2 FS 0.0 1.0 16 N  Sunny periods
13th
 8.5 17.2 17.0 56 8.2 0.5 1025.7 FS 0.0 1.8 16 N  Cloudy
14th
 12.4 19.6 16.9 61 9.4 2.8 1023.0 FS 0.0 2.6 18 N  Cloudy
15th
 13.3 16.2 15.3 88 13.4 0.2 1017.4 ST 9.1 2.2 20 N  Rain
16th
 13.6 18.8 18.3 65 11.6 1.8 1019.6 ST 1.8 2.6 18 N  Rain am
17th
 12.2 18.7 17.2 54 7.8 3.0 1019.8 FS 0.0 1.8 16 N  Cloudy
18th
 8.8 20.8 20.6 54 10.9 6.0 1015.9 FS 0.0 0.6 12 SW  Sunny pm
19th
 12.9 23.1 22.7 61 14.8 4.5 1014.0 ST 0.0 0.1 7 N  Fog am
20th
 14.3 20.4 18.9 63 11.7 1.5 1021.9 RS 0.0 0.6 10 N  Mist am, cloudy
21st
 12.8 21.5 21.5 47 9.7 6.5 1024.2 FS 0.0 1.6 12 SW  Sunny
22nd
 11.4 21.3 21.1 51 10.5 7.2 1023.0 FS 0.0 3.2 18 SW  Sunny
23rd
 15.7 18.8 18.4 73 13.5 0.5 1024.8 FS 0.0 1.5 11 SSW  Cloudy
24th
 10.7 19.7 19.1 43 6.2 7.8 1024.7 FS 0.3 0.6 13 N  Sunny
25th
 7.3 20.8 20.5 43 7.5 7.7 1025.5 FS 0.0 0.3 8 SSW  Sunny
26th
 6.4 21.1 20.8 45 8.4 7.5 1025.4 FS 0.0 0.1 6 N  Sunny
27th
 6.1 20.6 20.4 50 9.6 7.3 1025.9 FS 0.0 0.2 7 SSW  Sunny
28th
 7.9 17.9 17.3 60 9.4 2.3 1024.2 F 0.0 0.6 10 N  Cloudy
29th
 10.4 21.6 20.8 56 11.7 6.5 1020.2 FS 0.0 0.8 11 N  Sunny
30th
 12.4 17.3 16.9 69 11.2 0.0 1017.2 F 0.0 0.4 10 SSW  Cloudy
                         
‡ SUN: Sunshine hours are calculated approximately and solely from solar radiation readings, but note that the solar sensor's exposure to sunshine is rather limited. The sensor receives approx 65% of total possible sunshine exposure this month, and there is no allowance for sunshine by visual observation only, so the figures above can be very significantly less than the actual daily sunshine duration.
† Barometer trend (previous 3 hours) : F = falling, ST = steady, R = rising; Q = quickly, S = slowly†
‡ Weather Notes use METAR codes: OVC = overcast; SHRA = rain showers; '+' = heavy;